Project Summary/Abstract Following more than a decade of steady improvement, rates of mortality and severe retinopathy of prematurity (ROP) among extremely preterm infants in developed countries have not improved since 2012. One possible factor contributing to this is the clinical impact of the five Neonatal Oxygenation Prospective Meta-analysis (NeoPROM) trials, which reported that lower (85?89%) as compared to higher (91?95%) pulse oximeter saturation (SpO2) targets increased risk of mortality and severe necrotizing enterocolitis (NEC) but lowered risk of treated ROP. Although the NeoPROM results are controversial, many neonatal intensive care units (NICUs) in the United States and Europe have subsequently changed to higher SpO2 targets. Current targets vary greatly among NICUs, however, and whether these changes are translating into changing outcomes for preterm infants is unknown. Recent multicenter data suggest that increases in institutional SpO2 targets subsequent to publication of the NeoPROM trials are associated with increased local rates of severe ROP. Published studies examining the clinical impact of post-NeoPROM changes in SpO2 targets, however, are few, small, and contradictory. No large study has attempted to clarify the clinical impact of the NeoPROM trials by examining the relationship between recent NICU-specific changes in SpO2 targets and local changes in outcomes in preterm infants. The objective of this research is to link prospective survey data provided by California NICUs with existing data from the California Perinatal Quality Care Collaborative (CPQCC) database to examine associations between NICU-specific changes in policy-specified SpO2 targets and local changes in adverse outcomes of preterm birth. The study's specific aims are 1) to assess relationships between NICU-specific changes in SpO2 targets and infant outcomes following preterm birth in very low birth weight infants overall and in birth weight subgroups; and 2) to create an infrastructure for comparative effectiveness clinical trials, clinical research, and quality improvement related to supplemental oxygen therapy in California NICUs by defining their current oxygen saturation management practices and technical capabilities. We hypothesize that hospital-specific increases in SpO2 targets are associated with decreasing local risk for mortality and NEC and increasing local risk for ROP and ROP requiring treatment, after adjusting for potential confounders. The proposed research will accomplish these aims using a cohort of hospitals and preterm infants approximately 6-7 times larger than those in prior studies. This proposal is directly responsive to the goals of the NIH Small Research Grant Program (PA-17-299). The results of the proposed research will be foundational for subsequent research and funding applications, and will provide critical new evidence to inform clinical care and quality improvement efforts regarding supplemental oxygen therapy for preterm infants.